Glass ionomer compositions and methods including water-miscible, silane-treated, nano-sized silica particles

ABSTRACT

Disclosed herein are curable glass ionomer compositions that include a first paste and a second paste, and methods for using the disclosed compositions. The first paste includes water, a polyacid, and a non acid-reactive filler. The second paste includes water, an acid-reactive filler; and non-aggregated, water-miscible, nano-sized silica particles having at least 25% surface coverage of the particles with a silane. The composition is essentially free of a resin. In some embodiments, the water content of the first paste and the second paste of the paste/paste GI composition disclosed herein is less than 20% by weight, based on the total weight of the composition.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2018/031771, filed May 9, 2018, which claims the benefit of U.S.Provisional Application No. 62/507,874, filed May 18, 2017, thedisclosures of each of which are incorporated by reference herein intheir entireties.

BACKGROUND

Conventional Glass Ionomer (GI) compositions are dental materialscomposed of an acid-reactive filler such as a fluoroaluminosilicate(FAS) glass, a polyacid such as a water-soluble polymer with carboxylicgroups, and water. Acid groups in the polyacid can react with the metalcations from the acid-reactive filler in a “setting” reaction to form amatrix. When FAS glass is used as an acid-reactive filler, fluoride ionsare released as a byproduct. Many conventional GI compositions alsoincorporate a complexing agent such as tartaric acid to retard thesetting reaction. Although selecting specific acid-reactive fillers(e.g., compositions and/or particle size distributions), selectingspecific polyacids (e.g., compositions based on acrylic, maleic, and/oritaconic acids and acidic group content), and selecting the loadinglevel of the acid reactive filler in the GI composition can modify thereactivity of a GI composition, the selection of components has notresulted in major improvements in ease of mixing the components andstrength and aesthetics of the cured composition.

Both composites and conventional GI compositions can be used asrestorative materials. However, compared to composites, GI compositionscan offer advantages such as fluoride release, diminished sensitivity,and self-adherence to a tooth. However, compared to composites, lowmechanical properties and less desirable aesthetics have limited the useof GI compositions for many applications. Further, conventionalpowder/liquid GI compositions can be difficult to mix.

There is a continuing need for improved GI dental materials.

SUMMARY

In one aspect, the present disclosure provides curable glass ionomercompositions that include a first paste and a second paste. In oneembodiment, the curable glass ionomer composition includes: a firstpaste including water, a polyacid, and a non acid-reactive filler; and asecond paste including water, an acid-reactive filler; andnon-aggregated, water-miscible, nano-sized silica particles having atleast 25% surface coverage of the particles with a silane; wherein thecomposition is essentially free of a resin.

In another aspect, the present disclosure provides a device for storinga curable glass ionomer composition as described herein that includes afirst paste including water, a polyacid, and a non acid-reactive filler;and a second paste including water, an acid-reactive filler; andnon-aggregated, water-miscible, nano-sized silica particles having atleast 25% surface coverage of the particles with a silane; wherein thecomposition is essentially free of a resin. The device includes: a firstcompartment containing the first paste; and a second compartmentcontaining the second paste. In some embodiments, both the firstcompartment and the second compartment each independently includes anozzle or an interface for receiving an entrance orifice of a staticmixing tip.

In another aspect, the present disclosure provides a method of preparinga cured composition.

In one embodiment, the method includes providing a curable glass ionomercomposition as described herein that includes a first paste includingwater, a polyacid, and a non acid-reactive filler; and a second pasteincluding water, an acid-reactive filler; and non-aggregated,water-miscible, nano-sized silica particles having at least 25% surfacecoverage of the particles with a silane; wherein the composition isessentially free of a resin; combining the first paste and the secondpaste to form a mixture; and allowing the mixture to cure to form thecured composition.

In another embodiment, the method includes providing a device forstoring a curable glass ionomer composition as described herein thatincludes a first paste including water, a polyacid, and a nonacid-reactive filler; and a second paste including water, anacid-reactive filler; and non-aggregated, water-miscible, nano-sizedsilica particles having at least 25% surface coverage of the particleswith a silane; wherein the composition is essentially free of a resin,wherein the device includes a first compartment containing the firstpaste and a second compartment containing the second paste; combiningthe first paste and the second paste to form a mixture; and allowing themixture to cure to form the cured composition.

The curable paste/paste GI compositions disclosed herein canadvantageously provide improved storage stability compared to knownpaste/paste GI compositions, while retaining the mechanical strength(e.g., flexural strength and fracture toughness) typical of curedcompositions from known paste/liquid GI compositions due, for example,to low water content.

As used herein, the phrase “substantially crystalline inorganic fibers”refers to inorganic fibers that have minimal amorphous character (i.e.,substantially non-amorphous) as evidenced by a sharp x-ray diffraction(XRD) peak. The phrase “substantially crystalline inorganic fibers” isintended to exclude glassy fibers and glass ceramic fibers. In someembodiments, substantially crystalline inorganic fibers have acrystallinity index of at least 0.05, and in certain embodiments acrystallinity index of at least 0.1, as measured by the XRDCrystallinity Index Test Method as described herein. The CrystallinityIndex is a parameter used to characterize the level of crystallinitypresent in a sample of an inorganic fiber. In brief, in the XRDCrystallinity Index Test Method further described herein, tungstenpowder is used as internal standard. An internal or mass standard refersto a material incorporated into samples being evaluated to determinecrystallinity index, to normalize X-ray intensity values based on amountof material present in sample. Each inorganic fiber sample tested ismixed with tungsten powder in a 4:1 ratio by weight. Each inorganicfiber sample preparation is mixed as an ethanol slurry and then dried,and two sample preparations are made for each inorganic fiber sampletested. Six XRD scans of each sample preparation are then taken. Thecrystallinity index is the ratio of peak area observed for analytecrystalline phase diffraction peaks within the 14 to 46 degree (2Theta)scattering angle range and the (110) diffraction peak area for thetungsten internal standard.

As used herein, a “dental composition” or a “composition for dental use”or a “composition to be used in the dental field” refers to anycomposition that can be used in the dental field. In this respect thecomposition should be not detrimental to the patients' health and thusfree of hazardous and toxic components being able to migrate out of thecomposition. Dental compositions are typically hardenable compositionsthat can be hardened at ambient conditions, including a temperaturerange from about 15 to 50° C. or from about 20 to 40° C. within a timeframe of about 30 minutes or 20 minutes or 10 minutes. Highertemperatures are not recommended as they might cause pain to the patientand may be detrimental to the patient's health. Dental compositions aretypically provided to the practitioner in comparable small volumes, thatis volumes in the range from about 0.1 to about 100 ml or from about 0.5to about 50 ml or from about 1 to about 30 ml. Thus, the storage volumeof useful packaging devices is within these ranges.

As used herein, a “polymerizable component” refers to any component thatcan be cured or solidified, for example, by heating to causepolymerization or chemical crosslinking.

As used herein, the term “resin” refers to a polymerizable componentthat contains one, two, three, or more polymerizable groups. Exemplarypolymerizable groups include, but are not limited to, unsaturatedorganic groups, such as vinyl groups such as found in a (methyl)acrylategroup. A resin can often be cured by radiation induced polymerization orcrosslinking, or by using a redox initiator.

As used herein, the term “monomer” refers to any chemical substance thatcan be characterized by a chemical formula, bearing polymerizable groups(e.g., (meth)acrylate groups) that can be polymerized to oligomers orpolymers, thereby increasing the molecular weight. The molecular weightof monomers can typically be calculated from the given chemical formula.

As used herein, “(meth)acryl” is a shorthand term referring to “acryl”and/or “methacryl.” For example, a “(meth) acryloxy” group is ashorthand term referring to either an acryloxy group (i.e.,CH₂═CH—C(O)—O—) and/or a methacryloxy group (i.e., CH₂═C(CH₃)—C(O)—O—).

As used herein, the term “initiator” refers to a substance capable ofstarting or initiating a curing process for resins or monomers, forexample, by a redox/auto-cure chemical reaction, by a radiation inducedreaction, or by a heat induced reaction.

As used herein, the term “powder” refers to a dry, bulk solid composedof a large number of very fine particles that may flow freely whenshaken or tilted.

As used herein, the term “particle” refers to a substance being a solidhaving a shape that can be geometrically determined. Particles cantypically be analyzed with respect to, for example, grain size ordiameter.

The mean particle size of a powder can be obtained from varioustechniques including laser diffraction particle size analysis. Thecumulative curve of the grain size distribution can be obtained anddefined as the arithmetic average of the measured grain sizes of acertain powder mixture. Respective measurements can be done usingavailable diffraction laser particle size analyzers such as BeckmanCoulter LS 13320 Laser Diffraction Particle Size Analyzer orgranulometers such as CILAS Laser Diffraction Particle Size AnalysisInstrument.

As used herein, the term “dX” (micrometers) with respect to particlesize measurements means that X % of the particles in the analyzed volumehave a size below the indicated value in micrometers. For example, aparticle size value of 100 micrometers (d50) means that within theanalyzed volume, 50% of the particles have a size below 100 micrometers.

As used herein, the term “paste” refers to a soft, viscous mass ofsolids dispersed in a liquid.

As used herein, the term “viscous” refers to a material having aviscosity above about 3 Pa*s (at 23° C.).

As used herein, the term “liquid” refers to any solvent or liquid thatis able to at least partially disperse or dissolve a component atambient conditions (e.g., 23° C.). A liquid typically has a viscositybelow about 10 or below about 8 or below about 6 Pa*s.

As used herein, a “glass ionomer cement” or a “GIC” refers to a cementcapable of curing or hardening by the reaction between an acid-reactiveglass and a polyacid in the presence of water.

As used herein, a “resin modified glass ionomer cement” or “RM-GIC”refers to a GIC additionally containing a resin, an initiator system,and typically 2-hydroxylethyl methacrylate (HEMA).

As used herein, a “conventional glass ionomer cement or restorative”refers to a glass ionomer cement or restorative that is free of a resin,or essentially free of a resin.

As used herein, a composition is “essentially free of” or “substantiallyfree of” a certain component (e.g., a resin), if the composition doesnot contain said component as an essential feature. Thus, said componentis not intentionally added to the composition either as such or incombination with other components or ingredients of other components.

A composition being essentially free of a certain component (e.g., aresin) usually contains the component in an amount of less than about 5wt.-%, less than about 1 wt.-%, less than about 0.5 wt.-%, or less thanabout 0.01 wt.-%, with respect to the total weight of the composition ormaterial. The composition may not contain said component at all.

However, sometimes the presence of a small amount of the said componentcan be unavoidable, for example, due to impurities contained in the rawmaterials used.

As used herein, an “acid-reactive filler” refers to a filler that canchemically react in the presence of a polyacid leading to a hardeningreaction.

As used herein, a “non acid-reactive filler” refers to a filler, thatwhen mixed with a polyacid, (i) does not show a chemical reaction within6 minutes, or (ii) only shows a reduced (e.g., time-delayed) hardeningreaction.

To distinguish an acid-reactive filler from a non acid-reactive fillerthe following test can or is to be conducted: A composition is preparedby mixing a first part and a second part in a mass ratio of 1 to 3,wherein: the first part contains: poly (acrylic acid-co-maleic acid)(Mw: about 20,000+/−3,000): 43.6 wt.-%, water: 47.2 wt.-%, tartaricacid: 9.1 wt.-%, and benzoic acid: 0.1 wt.-%; and the second partcontains: filler to be analyzed: 100 wt.-%.

The filler is characterized as non acid-reactive, if within 6 minutesafter preparing the above composition the shear stress is less than50,000 Pa determined by conducting an oscillating measurement using arheometer under the following conditions: using an 8 millimeter plate,0.75 millimeter gap, at 28° C., frequency: 1.25 Hz, and deformation:1.75%.

As used herein “nanosilica” is used synonymously with “nano-sized silicaparticles,” and refers to silica particles having an average size of atmost 200 nanometers.

As used herein for a spherical particle, “size” refers to the diameterof the particle. As used herein for a non-spherical particle, “size”refers to the longest dimension of the particle.

As used herein, the term “silica sol” refers to a stable dispersion ofdiscrete, amorphous silica particles in a liquid, typically water.

As used herein, the terms “pyrogenic silica” and “fumed silica” are usedinterchangeably and refer to amorphous silicas formed in the vaporphase. Pyrogenic silica may contain, for example, a few hundred primaryparticles fused into branched-chain, three-dimensional aggregates.Examples of pyrogenic silica include products available under the tradedesignations AEROSIL OX-50, AEROSIL-130, AEROSIL-150, and AEROSIL-200available from DeGussa AG, (Hanau, Germany) and CAB-O-SIL M5 availablefrom Cabot Corp (Tuscola, Ill.).

As used herein, “non-pyrogenic silica” refers to amorphous silica thatis not formed in the vapor phase. Examples of non-pyrogenic silicasinclude precipitated silicas and silica gels.

As used herein, “silane treated” means that the surface of a particlehas been modified by application of a silane.

As used herein, “aggregated silica” is descriptive of an association ofprimary silica particles often bound together by, for example, residualchemical treatment, covalent chemical bonds, or ionic chemical bonds.Although complete breakdown of aggregated silica into smaller entitiesmay be difficult to achieve, limited or incomplete breakdown may beobserved under conditions including, for example, shearing forcesencountered during dispersion of the aggregated silica in a liquid.

As used herein a “cation reduced aluminosilicate glasses” refers to aglass having a lower content of cations in the surface region of theglass particle compared with the inner region of the glass particle.Such glasses typically react much slower upon contact with a solution ofpolyacrylic acid in water as compared to typical acid-reactive fillers.Examples of non acid-reactive fillers include quartz glass or strontiumoxide based glasses. Further examples are described herein. Cationreduction can be achieved by a surface treatment of the glass particles.Useful surface treatments include, but are not limited to, acid washing(e.g., treatment with a phosphoric acid), treatment with a phosphate,treatment with a chelating agent such as tartaric acid, and treatmentwith a silane or an acidic or basic silanol solution.

As used herein, the terms “polyacid” and/or “polyalkenoic acid” refer topolymers having a plurality of acidic repeating units (e.g., more than10 or more than 20 or more than 50). That is, the acidic repeating unitsare attached to or pending from the backbone of the polymer.

As used herein, the phrase “complexing agent” refers to a low molecularagent capable of forming a complex with metal ions such as, for example,calcium and/or magnesium. An exemplary complexing agent is tartaricacid.

As used herein, the terms “hardenable” and/or “curable” refer tocompositions that can be cured or solidified, for example, by conductinga glass ionomer cement reaction without the need for an additionalcuring system such as chemical cross-linking and/or radiation-inducedpolymerization or crosslinking.

As used herein, the phrase “ambient conditions” refers to conditions towhich paste/paste GI compositions as described herein are typicallysubjected during storage and handling. Ambient conditions may include,for example, a pressure of about 900 mbar to about 1100 mbar, atemperature of about −10° C. to about 60° C., and/or a relative humidityof about 10% to about 100%. In the laboratory ambient conditions aretypically adjusted to about 23° C. and about 1 atmosphere (e.g., 0.95 to1.05 atmosphere). In the dental and orthodontic field ambient conditionsare reasonably understood to include, for example, a pressure of about950 mbar to about 1050 mbar, a temperature of about 15° C. to about 40°C., and/or a relative humidity of about 20% to about 80%.

The terms “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims. Suchterms will be understood to imply the inclusion of a stated step orelement or group of steps or elements but not the exclusion of any otherstep or element or group of steps or elements. By “consisting of” ismeant including, and limited to, whatever follows the phrase “consistingof.” Thus, the phrase “consisting of” indicates that the listed elementsare required or mandatory, and that no other elements may be present. By“consisting essentially of” is meant including any elements listed afterthe phrase, and limited to other elements that do not interfere with orcontribute to the activity or action specified in the disclosure for thelisted elements. Thus, the phrase “consisting essentially of” indicatesthat the listed elements are required or mandatory, but that otherelements are optional and may or may not be present depending uponwhether or not they materially affect the activity or action of thelisted elements.

The words “preferred” and “preferably” refer to embodiments of thedisclosure that may afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the disclosure.

In this application, terms such as “a,” “an,” and “the” are not intendedto refer to only a singular entity, but include the general class ofwhich a specific example may be used for illustration. The terms “a,”“an,” and “the” are used interchangeably with the term “at least one.”

The phrases “at least one of” and “comprises at least one of” followedby a list refers to any one of the items in the list and any combinationof two or more items in the list.

As used herein, the term “or” is generally employed in its usual senseincluding “and/or” unless the content clearly dictates otherwise.

The term “and/or” means one or all of the listed elements or acombination of any two or more of the listed elements.

Also herein, all numbers are assumed to be modified by the term “about”and in certain situations by the term “exactly.” As used herein inconnection with a measured quantity, the term “about” refers to thatvariation in the measured quantity as would be expected by the skilledartisan making the measurement and exercising a level of carecommensurate with the objective of the measurement and the precision ofthe measuring equipment used. Also, as used herein in connection with ameasured quantity, the term “approximately” refers to that variation inthe measured quantity as would be expected by the skilled artisan makingthe measurement and exercising a level of care commensurate with theobjective of the measurement and the precision of the measuringequipment used.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range as well as the endpoints (e.g., 1to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentdisclosure. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Many powder/liquid GI compositions are difficult to mix due to highpowder/liquid ratios. When such difficulty in mixing is encountered,dentists sometimes lower the powder/liquid ratio below themanufacturer's recommendation to improve mixing properties. Althoughhand mixing properties may be improved, lowered powder/liquid ratiostypically result in decreased mechanical strength of the curedcomposition.

Disclosed herein are paste/paste GI compositions that can allow foreasier hand-mixing, as well as more reproducible and effective dosing ofthe ingredients. Further, in the paste/paste GI compositions disclosedherein, the second paste includes non-aggregated, water-miscible,nano-sized silica particles having at least 25% surface coverage of theparticles with a silane. The pastes including non-aggregated,water-miscible, nano-sized silica particles having at least 25% surfacecoverage of the particles with a silane can result in the compositionremaining sufficiently workable or mixable to form a curable glassionomer composition after storage at room temperature for at least onemonth, at least three months, or at least six months.

Known paste/paste GI compositions typically require a higher watercontent than comparable powder/liquid GI compositions, and the higherwater content often results in decreased mechanical strength of thecured composition. However, in the paste/paste GI compositions disclosedherein, in which the second paste includes non-aggregated,water-miscible, nano-sized silica particles having at least 25% surfacecoverage of the particles with a silane, the mechanical strength of thecured GI composition has been found to be equivalent, and in some casesgreater, than that for cured conventional powder/liquid GI compositions.Further, the paste/paste GI compositions disclosed herein, in which thesecond paste includes non-aggregated, water-miscible, nano-sized silicaparticles having at least 25% surface coverage of the particles with asilane, can retain the ease of mixing observed with other knownpaste/paste GI compositions.

Disclosed herein are curable glass ionomer compositions that include afirst paste and a second paste. The first paste includes water, apolyacid, and a non acid-reactive filler. The second paste includeswater, an acid-reactive filler; and non-aggregated, water-miscible,nano-sized silica particles having at least 25% surface coverage of theparticles with a silane. In certain embodiments, the GI composition isessentially free of a resin or free of a resin (e.g., a conventional GIcomposition). In some embodiments, the water content of the first pasteand the second paste of the paste/paste GI composition disclosed hereinis less than 20% by weight, based on the total weight of thecomposition. In some embodiments, the water content of the first pasteis less than 20% by weight, based on the total weight of the firstpaste; and the water content of the second paste is less than 20% byweight, based on the total weight of the second paste.

Polyacids

The first paste of the paste/paste GI compositions disclosed hereinincludes a polyacid. A wide variety of polyacids can be used in thepaste/paste GI compositions disclosed herein. In some embodiments, thepolyacid has a molecular weight sufficient to provide good storage,handling, and mixing properties, as well as to yield good materialproperties in the glass ionomer composition.

In one embodiment, the polyacid can be characterized by at least one ormore or all of the following parameters: being a solid (at 23° C.); andmolecular weight (Mw) of about 2,000 to about 250,000, or of about 5,000to about 100,000 (e.g., evaluated against a polyacrylic acid sodium saltstandard using gel permeation chromatography).

If the molecular weight of the polyacid is too high, obtaining aworkable consistency of the obtained paste when mixing the compositionscontained in the GI composition described herein might become difficult.Further, preparation of the compositions might become difficult. Inaddition, the obtained mixture or composition might become too sticky(e.g., adhere to the dental instrument used for application).

If the molecular weight of the polyacid is too low, the viscosity of theobtained paste might become too low and result in decreased mechanicalstrength.

Typically, the polyacid is a polymer having a plurality of acidicrepeating units.

Useful polyacids for the paste/paste GI compositions disclosed hereinare substantially free of polymerizable groups, or free of polymerizablegroups.

Useful polyacids need not be entirely water soluble, but typically theyare at least sufficiently water-miscible so that they do not undergosubstantial sedimentation when combined with other aqueous components.

The polyacid is hardenable in the presence of, for example, anacid-reactive filler and water, but preferably does not containethylenically unsaturated groups. That is, the polyacid is a polymerobtained by polymerizing an unsaturated acid. However, due to theproduction process, a polyacid might still contain unavoidable traces offree monomers (e.g., up to 1 or 0.5 or 0.3 wt.-% with respect to theamount of monomers used). Typically, the unsaturated acid is an oxyacid(i.e., an oxygen containing acid) of carbon, sulfur, phosphorous, orboron. More typically, it is an oxyacid of carbon. Useful polyacidsinclude, for example, polyalkenoic acids such as homopolymers andcopolymers of unsaturated mono-, di-, or tricarboxylic acids.

Polyalkenoic acids can be prepared by the homopolymerization andcopolymerization of unsaturated aliphatic carboxylic acids, e.g.,acrylic acid, methacrylic acid, itaconic acid, maleic acid, glutaconicacid, aconitic acid, citraconic acid, mesaconic acid, fumaric acid, andtiglic acid.

Useful polyacids also include alternating copolymers of maleic acid andethylene (e.g., in a molar one to one ratio).

Useful polyacids are also described in the following documents: U.S.Pat. No. 4,209,434 (Wilson et al.) and U.S. Pat. No. 4,360,605 (Schmittet al.).

Useful polyacids are also available, for example, as aqueous solutionsin the liquid component of products such as those available under thetrade designation KETAC FIL PLUS HANDMIX from 3M ESPE, or under thetrade designation FUJI IX GP HANDMIX from G-C Dental Industrial Corp.,Tokyo, Japan.

The amount of polyacid used in the paste/paste GI compositions disclosedherein should be sufficient to react with the acid-reactive filler, andto provide an ionomer composition with desirable hardening properties.

In certain embodiments, the polyacid is present in the first paste in anamount of at least 3 wt.-%, at least 5 wt.-%, or at least 10 wt.-%,based on the total weight of the first paste. In certain embodiments,the polyacid is present in the first paste in an amount of at most 70wt.-%, 60 wt.-%, or 50 wt.-%, based on the total weight of the firstpaste. In certain embodiments, the polyacid is present in the firstpaste in an amount of 3 wt.-% to 70 wt.-%; 5 wt.-% to 60 wt.-%, or 10wt.-% to 50 wt.-%, based on the total weight of the first paste.

If the amount of the polyacid is too high, obtaining a workableconsistency of the obtained paste when mixing the compositions containedin the paste/paste GI composition disclosed herein might becomedifficult. Further, preparation of the compositions might becomedifficult. In addition, the obtained mixture or composition might becometoo sticky (e.g., adheres to the dental instrument used forapplication).

If the amount of the polyacid is too low, obtaining a workableconsistency of the obtained paste when mixing the compositions containedin the paste/paste GI composition disclosed herein might becomedifficult. Further, it will become difficult to achieve the desiredmechanical properties.

Non Acid-Reactive Fillers

The first paste of the paste/paste GI compositions disclosed hereinincludes a non acid-reactive filler. The second paste of the paste/pasteGI compositions disclosed herein also includes a non acid-reactivefiller that is the same as or different than the non acid-reactivefiller in the first paste. The non-acid reactive filler can include, forexample, particles and/or fibers (e.g., substantially crystallineinorganic fibers as described herein below).

A non acid-reactive filler is a filler that when combined with apolyacid in the presence of water either (i) does not cure in a glassionomer cement reaction at all, or (ii) that only shows a delayed curingreaction.

A wide variety of non acid-reactive fillers can be used in thepaste/paste GI compositions disclosed herein. In certain embodiments,the non acid-reactive filler is an inorganic filler. In certainembodiments, the non acid-reactive filler is non-toxic and suitable foruse in the mouth of a human being. A non acid-reactive filler can beradiopaque or radiolucent. Optionally, the surface of the particles of anon acid-reactive filler can be surface treated (e.g., with silanes).

In certain embodiments, the non acid-reactive filler can include quartz,nitrides, kaolin, borosilicate glass, strontium oxide based glass,barium oxide based glass, silica, alumina, titania, zirconia, or acombination thereof.

In certain embodiments, the non acid-reactive filler can include a metaloxide such as alumina, silica, zirconia, titania, or a combinationthereof. In some embodiments the metal oxide can further includemodifiers or dopants such as sodium, magnesium, lithium, calcium,strontium, barium, yttrium, ytterbium, lanthanum, zinc, iron, manganese,bismuth oxides, or a combination thereof.

In certain embodiments, the non acid-reactive filler has a mean particlesize of 0.005 micrometer to 20 micrometers. For some embodiments, thenon acid-reactive filler has a mean particle size of 0.01 micrometer to10 micrometers. In certain embodiments, the non acid-reactive filler hasa d50 of less than 10 micrometers. For embodiments in which both thefirst paste and the second paste include a non acid-reactive fillers,the mean particle size of the non acid-reactive filler in the secondpaste can be the same or different than the mean particle size of thenon acid-reactive filler in the first paste.

Exemplary non acid-reactive filler are further described, for example,in International Application Publication No. WO 2017/015193 A1 (Jahns etal.).

In certain embodiments, the non acid-reactive filler can be provided asa dispersion or sol of particles in a liquid (e.g., water). If thefiller is provided as an aqueous dispersion or sol, the amount of waterin the aqueous dispersion or sol has to be taken into account when theamount of water and filler in the composition is calculated ordetermined.

In certain embodiments, the non acid-reactive filler can includenon-aggregated, water-miscible, nano-sized silica particles having atleast 25% surface coverage of the particles with a silane, as furtherdiscussed herein below.

For the paste/paste GI compositions disclosed herein, the first pasteincludes at least 10 wt.-% non acid-reactive filler, at least 25 wt.-%non acid-reactive filler, or at least 35 wt.-% non acid-reactive filler,based on the total weight of the first paste. For the paste/paste GIcompositions disclosed herein, the first paste includes at most 80 wt.-%non acid-reactive filler, at most 70 wt.-% non acid-reactive filler, orat most 60 wt.-% non acid-reactive filler, based on the total weight ofthe first paste.

For the paste/paste GI compositions disclosed herein, the second pasteincludes a non acid-reactive filler, which may include, among otherfillers, non-aggregated, water-miscible, nano-sized silica particleshaving at least 25% surface coverage of the particles with a silane. Thesecond paste includes at least 1 wt.-% non acid-reactive filler, atleast 3 wt.-% non acid-reactive filler, or at least 5 wt.-% nonacid-reactive filler, based on the total weight of the second paste. Forthe paste/paste GI compositions disclosed herein, the second pasteincludes at most 50 wt.-% non acid-reactive filler, at most 40 wt.-% nonacid-reactive filler, or at most 30 wt.-% non acid-reactive filler,based on the total weight of the second paste.

Nano-Sized Silica Particles

In the glass ionomer compositions disclosed herein, the second pasteincludes non-aggregated, water-miscible, nano-sized silica particleshaving at least 25% surface coverage of the particles with a silane. Insome embodiments, the non-aggregated, nano-sized silica particles aresubstantially free of fumed silica (i.e., pyrogenic silica). Howeverpyrogenic fillers (e.g., fumed silica) can be added as optionaladditives to the dental compositions.

A wide variety of non-aggregated, nano-sized silica particles can besurface treated as described herein. In some embodiments, thenon-aggregated, nano-sized silica particles are available as a silicasol. In certain embodiments, the starting silica sol is NALCO 2329 orLEVASIL 50/50.

Exemplary non-aggregated, nano-sized silica particles include thoseavailable from Nalco Chemical Co. (Naperville, Ill.) under the productdesignation NALCO COLLOIDAL SILICAS (e.g., NALCO products 1040, 1042,1050, 1060, 2327 and 2329), Nissan Chemical America Company, Houston,Tex. (e.g., SNOWTEX-ZL, -OL, -O, -N, -C, -20L, -40, and -50); AdmatechsCo., Ltd., Japan (e.g., SX009-MIE, SX009-MIF, SC1050-MJM, andSC1050-MLV); Grace GmbH & Co. KG, Worms, Germany (e.g., those availableunder the product designation LUDOX, e.g., P-W50, P-W30, P-X30, P-T40and P-T40AS); Akzo Nobel Chemicals GmbH, Leverkusen, Germany (e.g.,those available under the product designation LEVASIL, e.g., 50/50,100/45, 200/30%, 200A/30, 200/40, 200A/40, 300/30 and 500/15), and BayerMaterial Science AG, Leverkusen, Germany (e.g., those available underthe product designation DISPERCOLL S, e.g., 5005, 4510, 4020 and 3030).Further exemplary fillers including non-aggregated, nano-sized silicaparticles and methods of preparing the fillers are disclosed in, forexample, International Publication No. WO 01/30307 (Craig et al.).

For embodiments in which the dental composition further includespyrogenic fillers (e.g., fumed silica), a wide variety of pyrogenicfillers such as fumed silica can be used. Exemplary fumed silicasinclude for example, products sold under the trade designations AEROSILseries OX-50, -130, -150, and -200, Aerosil R8200 available from DegussaAG, (Hanau, Germany), CAB-O-SIL M5 available from Cabot Corp (Tuscola,Ill.), and HDK types, e.g. HDK-H 2000, HDK H15; HDK H18, HDK H20 and HDKH30 available from Wacker.

In one embodiment, the non-aggregated, nano-sized silica particles havean average particle size of at most about 200 nanometers, in someembodiments at most about 150 nanometers, and in certain embodiments atmost about 120 nanometers. In one embodiment, the non-aggregated,nano-sized silica particles have an average particle size of at leastabout 20 nanometers, in some embodiments at least about 50 nanometers,and in certain embodiments at least about 70 nanometers. Thesemeasurements can be based on a TEM (transmission electron microscopy)method, whereby a population of particles is analyzed to obtain anaverage particle size.

An exemplary method for measuring the particle diameter can be describedis as follows:

Samples approximately 80 nm thick are placed on 200 mesh copper gridswith carbon stabilized formvar substrates (SPI Supplies—a division ofStructure Probe, Inc., West Chester, Pa.). A transmission electronmicrograph (TEM) is taken, using JEOL 200CX (JEOL, Ltd. of Akishima,Japan and sold by JEOL USA, Inc.) at 200Kv. A population size of about50-100 particles can be measured and an average diameter can bedetermined.

In one embodiment, the average surface area of the non-aggregated,nano-sized silica particles is at least about 15 m²/g, and in someembodiments at least about 30 m²/g.

In some embodiments, the non-aggregated, nano-sized silica particlesused in the dental pastes disclosed in the present application aresubstantially spherical and substantially non-porous. Although thesilica may be essentially pure in certain embodiments, it may containsmall amounts of stabilizing ions such as ammonium and alkaline metalions in other embodiments.

The non-aggregated, nano-sized silica particles can be surface treatedwith a silane that can provide for water-miscibility of the treatedparticles. Surface-treating the nano-sized silica particles beforeloading into the dental material can provide a more stable dispersion inthe paste. Preferably, the surface-treatment stabilizes the nano-sizedsilica particles so that the particles will be well dispersed in thepaste and result in a substantially homogeneous composition. Exemplarymethods of surface treating drying nano-sized silica particles aredescribed in U.S. Pat. No. 6,899,948 B2 (Zhang et al.) and EP 0368 657A2 (Okada et al.).

In certain embodiments, the silane is essentially free of unsaturatedpolymerizable groups.

In certain embodiments, the silane is of the formula:(R¹O)₃—Si—(CH₂)_(n)—(O-R²)_(x)—OR³, wherein: R¹ is a C1-C3 alkyl group;R² is a C2-C3 alkylene group; R³ is a C1-C10 alkyl group; n=2 to 6; andx=0 to 200. In certain embodiments, R² represents —CH₂CH₂—. In certainembodiments, n=3.

In other certain embodiments, the silane is of the formula:(R¹O)₃—Si—(CH₂)_(n)—(O—R²)_(x)—OR³, wherein: R¹ is a C1-C3 alkyl group;R² is a C2-C3 alkylene group; R³ is 2,3-epoxypropyl; n=2 to 6; and x=0to 200.

Exemplary silanes include, for example, SILQUEST A-1230 available fromMomentive Performance Materials (Waterford, N.Y.);2-[methoxy-(polyethyleneoxy)₆₋₉propyl]trimethoxysilane,2-[methoxy-(polyethyleneoxy)₉₋₁₂ propyl]trimethoxysilane, and[3-(2,3-epoxypropoxy)propyl]trimethoxysilane (i.e.,3-glycidoxyproplytrimethoxysilane) available from Gelest (Morrisville,Pa.).

The non-aggregated, water-miscible, nano-sized silica particles have atleast 25% surface coverage of the particles with a silane. In someembodiments, the non-aggregated, water-miscible, nano-sized silicaparticles have at least 50% surface coverage of the particles with asilane. In certain embodiments, the non-aggregated, water-miscible,nano-sized silica particles have at least 75% surface coverage of theparticles with a silane. In some certain embodiments, thenon-aggregated, water-miscible, nano-sized silica particles have atleast 95% surface coverage of the particles with a silane.

The ratio of silane to silica sol for a “100% theoretical coverage” canbe calculated using Equation 1 shown below:

$\begin{matrix}{\frac{g\mspace{14mu}{silane}}{g\mspace{14mu}{silica}\mspace{14mu}{sol}} = {6.25 \times 10^{{- 4}\mspace{11mu}{mol}}\text{/}g \times \frac{20\mspace{14mu}{nm}}{d} \times {MW} \times {SiO}\; 2\mspace{14mu} w\text{/}w}} & (1)\end{matrix}$Where d is the diameter of the silica particle (nm), MW is the molecularweight of the silane (g/mol), and SiO₂ w/w is the silica weight fractionof the silica sol (w/w).

For example, using Levasil 50/50 as the silica sol and3-glycidoxypropyltrimethoxysilane as the silane, the ratio for “^(100%)theoretical coverage” is calculated as follows:

$\begin{matrix}{\frac{g\mspace{14mu}{silane}}{g\mspace{14mu}{Levasil}\mspace{14mu} 50\text{/}50} = {6.25 \times 10^{- 4}\mspace{14mu}{mol}\text{/}g \times \frac{20\mspace{14mu}{nm}}{50\mspace{14mu}{nm}} \times}} \\{236.3\mspace{14mu} g\text{/}{mol} \times 0.5} \\{= {{.03}\;\frac{g\mspace{14mu}{silane}}{g\mspace{14mu}{Levasil}\mspace{14mu} 50\text{/}50}}}\end{matrix}$

In an exemplary method, the calculated amounts of silica sol and silanecan be added into a vessel (e.g., a glass vial or glass jar), and thesolution can be allowed to react. Although the reaction temperature andtime can vary widely as desired, exemplary reaction conditions can be80-85° C. for 17 hours. Once the reaction is complete, thesilane-treated silica sol can be used as is.

For the paste/paste GI compositions disclosed herein, the second pasteincludes non-aggregated, water-miscible, nano-sized silica particleshaving at least 25% surface coverage of the particles with a silane. Thesecond paste includes at least 1 wt.-%, at least 3 wt.-%, or at least 5wt.-% of the non-aggregated, water-miscible, nano-sized silica particleshaving at least 25% surface coverage of the particles with a silane,based on the total weight of the second paste. For the paste/paste GIcompositions disclosed herein, the second paste includes at most 50wt.-%, at most 40 wt.-%, or at most 30 wt.-% of the non-aggregated,water-miscible, nano-sized silica particles having at least 25% surfacecoverage of the particles with a silane, based on the total weight ofthe second paste.

Acid-Reactive Fillers

The second paste of the paste/paste GI compositions disclosed hereinincludes an acid-reactive filler.

A wide variety of acid-reactive fillers can be used in the paste/pasteGI compositions disclosed herein. The acid-reactive filler can undergo aglass-ionomer cement reaction with a polyacid and water.

Useful acid-reactive fillers include, for example, metal oxides, metalhydroxides, hydroxyapatite, acid-reactive glasses, and combinationsthereof. In certain embodiments, the acid-reactive fillers include, forexample, inorganic fillers selected from the group consisting of basicmetal oxides, metal hydroxides, hydroxyapatite, aluminosilicate glasses,fluoroaluminosilicate glasses, glasses having a Si/Al weight percentratio less than 1.5, and combinations thereof. Useful metal oxidesinclude, for example, calcium hydroxide, magnesium hydroxide, strontiumhydroxide and mixtures thereof.

In certain embodiments the acid-reactive filler is afluoroaluminosilicate (“FAS”) glass. FAS glasses typically contains asufficient amount of elutable cations such that a hardened dentalcomposition can be obtained when the glass is mixed with the othercomponents of the hardenable composition. In some embodiments, the FASglass also contains a sufficient amount of elutable fluoride ions sothat the hardened composition will have cariostatic properties.

FAS glass can be made from a melt containing fluoride, silica, alumina,and other glass-forming ingredients using techniques familiar to thoseskilled in the FAS glassmaking art. See, for example, U.S. Pat. No.4,376,835 (Schmitt et al.) and U.S. Pat. No. 5,250,585 (Guggenberger etal.). In some embodiments, FAS glasses can be prepared by fusingmixtures of silica, alumina, cryolite and fluorite. The FAS glasstypically is in the form of particles that are sufficiently finelydivided so that they can conveniently be mixed with the other cementcomponents and will perform well when the resulting mixture is used inthe mouth.

Useful FAS glasses are known in the art and are available from a widevariety of sources, and many are found in currently available glassionomer cements such as, for example, those available under the tradedesignations KETAC-MOLAR or KETAC-FIL PLUS from 3M ESPE Dental, andunder the trade designation FUJI-IX available from G-C Dental IndustrialCorp., Tokyo, Japan.

In certain embodiments, the acid-reactive filler has a mean particlesize of 3 micrometers to 10 micrometers. If the mean particle size ofthe acid-reactive filler is above this range, the consistency of thecomposition obtained when mixing the compositions contained in thepaste/paste GI composition described herein may be less than desired,and the mechanical properties may be less than desired. If the meanparticle size of the acid-reactive filler is below this range, thesetting time of the paste/paste GI compositions described herein may befaster than desired.

Exemplary acid-reactive fillers are further described, for example, inInternational Application Publication No. WO 2015/088956 A1 (Peez etal.).

For the paste/paste GI compositions disclosed herein, the second pasteincludes at least 40 wt.-% acid-reactive filler, at least 50 wt.-%acid-reactive filler, or at least 60 wt.-% acid-reactive filler, basedon the total weight of the second paste. For the paste/paste GIcompositions disclosed herein, the second paste includes at most 90wt.-% acid-reactive filler, at most 88 wt.-% acid-reactive filler, or atmost 86 wt.-% acid-reactive filler, based on the total weight of thesecond paste.

If the amount of the acid-reactive filler is too high, the pastes of thepaste/paste GI compositions described herein may not be adequatelymixed, and obtaining an adequate consistency and acceptable mechanicalproperties of the resulting composition might become difficult.

If the amount of the acid-reactive filler is too low, a useful paste maynot be obtained by mixing the respective pastes of the paste/paste GIcompositions described herein. Further, the mechanical strength of thecured composition might decrease.

Substantially Crystalline Inorganic Fibers

In some embodiments of the paste/paste GI compositions disclosed herein,at least one of the first paste and the second paste includessubstantially crystalline inorganic fibers.

Substantially crystalline inorganic fibers include inorganic fibers thathave minimal amorphous character (i.e., substantially non-amorphous) asevidenced by a sharp x-ray diffraction (XRD) peak. Glassy fibers andglass ceramic fibers are typically not substantially crystallineinorganic fibers. In some embodiments, substantially crystallineinorganic fibers have a crystallinity index of at least 0.05, and incertain embodiments a crystallinity index of at least 0.1, as measuredby the XRD Crystallinity Index Test Method as described herein. TheCrystallinity Index is a parameter used to characterize the level ofcrystallinity present in a sample of an inorganic fiber. In brief, inthe XRD Crystallinity Index Test Method further described herein,tungsten powder is used as internal standard. An internal or massstandard refers to a material incorporated into samples being evaluatedto determine crystallinity index, to normalize X-ray intensity valuesbased on amount of material present in sample. Each inorganic fibersample tested is mixed with tungsten powder in a 4:1 ratio by weight.Each inorganic fiber sample preparation is mixed as an ethanol slurryand then dried, and two sample preparations are made for each inorganicfiber sample tested. Six XRD scans of each sample preparation are thentaken. The crystallinity index is the ratio of peak area observed foranalyte crystalline phase diffraction peaks within the 14 to 46 degree(2Theta) scattering angle range and the (110) diffraction peak area forthe tungsten internal standard.

A wide variety of substantially crystalline inorganic fibers can beused, including ceramic fibers and/or metal oxide fibers. Forembodiments in which the substantially crystalline inorganic fibersinclude metal oxide fibers, a wide variety of metal oxides can be used.Exemplary metal oxides include, but are not limited to, alumina, silica,zirconia, titania, and combinations thereof. Mixed metal oxides such asaluminosilicates typically contain no more than 20% by weight silicates,based on the total weight of the mixed metal oxide to avoid substantialformation of glassy domains. Optionally, the metal oxide can be modified(e.g., doped) with a component selected from the group consisting ofsodium, magnesium, lithium, calcium, strontium, barium, yttrium,ytterbium, lanthanum, zinc, iron, manganese, bismuth oxides, andcombinations thereof. For embodiments in which the metal oxide includesa modifier or dopant component, the component is typically present at nomore than 10% by weight, based on the total weight of the metal oxide toavoid substantial formation of glassy domains.

In certain embodiments of the paste/paste GI compositions disclosedherein, the substantially crystalline inorganic fibers as contained inthe pastes have an average diameter of at least 3 micrometers.

In certain embodiments of the paste/paste GI compositions disclosedherein, the substantially crystalline inorganic fibers as contained inthe pastes have an average diameter of at most 25 micrometers, or atmost 20 micrometers.

In some embodiments of the paste/paste GI compositions disclosed herein,the substantially crystalline inorganic fibers as contained in thepastes have an average aspect ratio of no more than 100:1, no more than50:1, no more than 25:1, or no more than 15:1.

In certain embodiments of the paste/paste GI compositions disclosedherein, the substantially crystalline inorganic fibers as contained inthe pastes have an average aspect ratio of 10:1 to 50:1, or 15:1 to25:1. In some certain embodiments of the paste/paste GI compositionsdisclosed herein, the substantially crystalline inorganic fibers ascontained in the pastes have an average aspect ratio of about 10:1.

In certain embodiments of the paste/paste GI compositions disclosedherein, the substantially crystalline inorganic fibers as contained inthe pastes have an average length of no more than 1 millimeter, or nomore than 0.5 millimeter.

In certain embodiments of the paste/paste GI compositions disclosedherein, the substantially crystalline inorganic fibers as contained inthe pastes have an average length of at least 25 micrometers.

In certain embodiments of the paste/paste GI compositions disclosedherein, the first paste includes no more than 65% by weight of thesubstantially crystalline inorganic fibers, based on the total weight ofthe first paste.

In certain embodiments of the paste/paste GI compositions disclosedherein, the second paste includes no more than 65% by weight of thesubstantially crystalline inorganic fibers, based on the total weight ofthe second paste.

In certain embodiments of the paste/paste GI compositions disclosedherein, the composition includes no more than 40% by weight of thesubstantially crystalline inorganic fibers, based on the total weight ofthe composition.

In certain embodiments of the paste/paste GI compositions disclosedherein, the composition includes 10% by weight to 15% by weight of thesubstantially crystalline inorganic fibers, based on the total weight ofthe composition.

Water Content

The water in the paste/paste GI compositions disclosed herein can bedistilled, de-ionized, or plain tap water. Typically, de-ionized wateris used. The amount of water should be sufficient to provide adequatehandling and mixing properties and to permit the transport of ions,particularly in the cement reaction.

If the amount of the water is too low, obtaining a workable consistencyof the obtained paste might become difficult. If the amount of water istoo high, obtaining of a workable consistency of the obtained pastemight become difficult, too. Further, it may become difficult to achievethe desired mechanical properties.

For some embodiments of the paste/paste GI compositions disclosedherein, the water content of the first paste and the second pastecombined is less than 20% by weight, less than 19% by weight, less than18% by weight, less than 17% by weight, less than 16% by weight, or lessthan 15% by weight, based on the total weight of the composition.

In certain embodiments of the paste/paste GI compositions disclosedherein, the water content of the first paste and the second pastecombined is at least 10% by weight, and in some embodiments at least 15%by weight, based on the total weight of the composition.

In certain embodiments of the paste/paste GI compositions disclosedherein, the water content of the first paste is less than 20% by weight,less than 19% by weight, less than 18% by weight, less than 17% byweight, less than 16% by weight, or less than 15% by weight, based onthe total weight of the first paste.

In certain embodiments of the paste/paste GI compositions disclosedherein, the water content of the second paste is less than 20% byweight, less than 19% by weight, less than 18% by weight, less than 17%by weight, less than 16% by weight, or less than 15% by weight, based onthe total weight of the second paste.

Optional Complexing Agent

In certain embodiments, the first paste may optionally include acomplexing agent.

For embodiments in which the first paste includes a complexing agent, awide variety of complexing agents can be used. Useful complexing agentcan be characterized by one or more of: being soluble in water (at least50 g/l water at 23° C.); having a molecular weight of 50 g/mol to 500g/mol, or having a molecular weight of from 75 g/mol to 300 g/mol.

Exemplary complexing agents include, but are not limited to, tartaricacid, citric acid, ethylene diamine tetra acetic acid (EDTA), salicylicacid, mellitic acid, dihydroxy tartaric acid, nitrilotriacetic acid(NTA), 2,4 and 2,6 dihydroxybenzoic acid, phosphono carboxylic acids,phosphono succinic acid and mixtures thereof. Further examples ofcomplexing agents can be found, for example, U.S. Pat. No. 4,569,954(Wilson et al.).

For embodiments of the paste/paste GI composition disclosed herein inwhich the first paste includes a complexing agent, the first pasteincludes at least 0.1 wt.-% complexing agent, at least 1.0 wt.-%complexing agent, or at least 1.5 wt.-% complexing agent, based on thetotal weight of the first paste. For the paste/paste GI compositionsdisclosed herein in which the first paste includes a complexing agent,the first paste includes at most 12 wt.-% complexing agent, at most 10wt.-% complexing agent, or at most 8 wt.-% complexing agent, based onthe total weight of the first paste.

Optional Additives

The paste/paste GI compositions disclosed herein may optionally includevarious additives known in the art including, but not limited to,flavorants, fluoridating agents, buffering agents, numbing agents,remineralization agents, desensitization agents, colorants,indicator(s), viscosity modifiers, surfactants, stabilizers,preservative agents (e.g., benzoic acid), or combinations thereof. Thepresence of a colorant can aid in detecting that the aqueous compositionhas coated all the desired intraoral surfaces. The intensity of acolorant can also aid in detecting the uniformity of the coating on theintraoral surfaces.

For embodiments of the paste/paste GI composition disclosed herein inwhich an additive is present in the first paste, the first pasteincludes at least 0.01 wt.-% additive, at least 0.05 wt.-% additive, orat least 0.1 wt.-% additive, based on the total weight of the firstpaste. For the paste/paste GI compositions disclosed herein in which anadditive is present in the first paste, the first paste includes at most5 wt.-% additive, at most 3 wt.-% additive, or at most 1 wt.-% additive,based on the total weight of the first paste.

For embodiments of the paste/paste GI composition disclosed herein inwhich an additive is present in the second paste, the second pasteincludes at least 0.01 wt.-% additive, at least 0.05 wt.-% additive, orat least 0.1 wt.-% additive, based on the total weight of the secondpaste. For the paste/paste GI compositions disclosed herein in which anadditive is present in the second paste, the second paste includes atmost 5 wt.-% additive, at most 3 wt.-% additive, or at most 1 wt.-%additive, based on the total weight of the second paste.

Typically neither the first paste nor the second paste of thepaste/paste GI composition disclosed herein contains any of thefollowing components, alone or in combination: a) HEMA in an amountabove 1 wt.-% or above 0.5 wt.-%; b) resin(s) in an amount above 1 wt.-%or above 0.5 wt.-%; c) initiator component(s) suitable to cure resin(s)or monomer(s) in an amount above 1 wt.-% or above 0.5 wt.-%; d)inhibitor(s) like methoxyphenol or 3,5-Di-tert-butyl-4-hydroxytoluol inan amount above 1 wt.-% or above 0.5 wt.-%; e) desiccant(s) likezeolithe(s) in an amount above 1 wt.-% or above 0.5 wt.-%. Thus, thecomposition obtained when mixing the pastes of the paste/paste GIcomposition is not a resin-modified glass ionomer cement (RM-GIC), andthus does not contain a curing system based on polymerization.

Accordingly, in certain embodiments, the paste/paste GI compositionsdisclosed herein do not contain a redox-initiator system or a thermallyinduced initiator system or a radiation induced initiator system.

First Paste and Second Paste

The first paste can typically be characterized by having a pH less than7.

The second paste can typically be characterized by having a pH greaterthan 7.

Optionally, the first paste and/or the second paste can eachindependently further include a solvent. In some embodiments, adding asolvent or co-solvent can help to adjust the viscosity and consistencyof the composition.

Examples of useful solvents include alcohols (e.g., methanol, ethanol,and propanol), polyalcohols/polyols (e.g., ethylene glycol andglycerol), and combinations thereof.

Devices

The first paste and the second paste of the paste/paste GI compositionsdescribed herein can be provided to the practitioner in variousembodiments.

In one embodiment, the pastes may be contained in separate sealablevessels (e.g., made out of plastic or glass). For use, the practitionermay take adequate portions of the paste components from the vessels andmix the portions by hand on a mixing plate.

In some embodiments, the pastes are contained in separate compartmentsof a storage device. The storage device typically includes twocompartments for storing the respective pastes, each compartment beingequipped with a nozzle for delivering the respective paste. Oncedelivered in adequate portions, the pastes can then be mixed by hand ona mixing plate.

In certain embodiments, the storage device has an interface forreceiving a static mixing tip. The mixing tip is used for mixing therespective pastes. Static mixing tips are available from, for example,SulzerMixpac Company. Useful storage devices include cartridges,syringes, and tubes.

The storage device typically includes two housings or compartmentshaving a front end with a nozzle and a rear end and at least one pistonmovable in the housing or compartment.

Useful cartridges are described, for example, in U.S. Patent ApplicationPub. No. 2007/0090079 A1 (Keller et al.) and U.S. Pat. No. 5,918,772(Keller et al.). Useful cartridges are available from, for example,SulzerMixpac AG (Switzerland). Useful static mixing tips are described,for example, in U.S. Patent Application Pub. No. 2006/0187752 A1 (Kelleret al.) and in U.S. Pat. No. 5,944,419 (Streiff). Useful mixing tips areavailable from, for example, SulzerMixpac AG (Switzerland).

Other useful storage devices are described, for example, in WO2010/123800 (3M), WO 2005/016783 (3M), WO 2007/104037 (3M), WO2009/061884 (3M).

Alternatively, paste/paste GI compositions described herein can beprovided in two individual syringes and the individual pastes can bemixed by hand prior to use.

In certain embodiments the paste/paste GI composition disclosed hereincan be provided as a kit that includes the first paste, the secondpaste, and instructions describing one or more methods (as disclosedherein) for mixing the first paste and the second paste to form a curedcomposition.

In one embodiment, the present disclosure provides a device for storinga curable glass ionomer composition as described herein that includes afirst paste including water, a polyacid, and a non acid-reactive filler;and a second paste including water, an acid-reactive filler; andnon-aggregated, water-miscible, nano-sized silica particles having atleast 25% surface coverage of the particles with a silane; wherein thecomposition is essentially free of a resin. The device includes: a firstcompartment containing the first paste; and a second compartmentcontaining the second paste. In some embodiments, both the firstcompartment and the second compartment each independently includes anozzle or an interface for receiving an entrance orifice of a staticmixing tip.

In some embodiments, the mixing ratio of first paste and the secondpaste is 1:3 to 2:1 with respect to volume, and in certain embodiments,1:2 to 2:1 with respect to volume.

In other embodiments, the mixing ratio of first paste and the secondpaste is 1:6 to 1:1 with respect to weight, and in certain embodiments1:4 to 1:1 with respect to weight.

The composition obtained or obtainable when mixing the respective pastesis in particular useful as or for producing a dental cement, dentalfilling material, dental core build up material or as dental rootchannel filling material.

Methods

A practitioner can use the paste/paste GI compositions disclosed hereinin a wide variety of methods to prepare a cured composition.

In one embodiment, the method includes: providing a curable glassionomer composition as described herein that includes a first pasteincluding water, a polyacid, and a non acid-reactive filler; and asecond paste including: water, an acid-reactive filler; andnon-aggregated, water-miscible, nano-sized silica particles having atleast 25% surface coverage of the particles with a silane; wherein thecomposition is essentially free of a resin; combining the first pasteand the second paste to form a mixture (e.g., a hardenable composition);and allowing the mixture to cure to form the cured composition.

In another embodiment, the method includes: providing a device forstoring a curable glass ionomer composition as described herein thatincludes a first paste including water, a polyacid, and a nonacid-reactive filler; and a second paste including water, anacid-reactive filler; and non-aggregated, water-miscible, nano-sizedsilica particles having at least 25% surface coverage of the particleswith a silane; wherein the composition is essentially free of a resin,wherein the device includes: a first compartment containing the firstpaste; and a second compartment containing the second paste; combiningthe first paste and the second paste to form a mixture (e.g., ahardenable composition); and allowing the mixture to cure to form thecured composition.

In certain embodiments, the mixture (e.g., hardenable composition) isapplied to the surface of hard dental tissue, and the mixture (e.g.,hardenable composition) is allowed to cure and form a cured compositionon the surface of the hard dental tissue.

According to one embodiment the cement composition obtained orobtainable by mixing the two pastes of the GI composition disclosedherein can fulfil at least one, more than one, or all of the followingparameters before or during hardening: setting time within about 5minutes, 4 minutes, or 3 minutes determined according to EN-ISO9917-1:2007; working time within about 4 minutes, 3 minutes, 2 minutes,or 1 minute determined according to EN-ISO 9917-1:2007; and beingstorage stable. If desired, the setting time and curing behavior can bedetermined as described in more detail in the Example section herein.

In certain embodiments, the mixture (e.g., hardenable composition)formed from mixing the first paste and the second paste of thepaste/paste GI composition disclosed herein has a sufficient workingtime to allow the practitioner not only to adequately mix thecomposition, but also to apply the composition to the surface of, forexample, a crown, bridge, root canal or prepared tooth. Further, themixture (e.g., hardenable composition) has a conveniently short settingtime that can save time for the practitioner and enhance convenience forthe patient.

According to another embodiment, the mixture (e.g., hardenablecomposition) formed from mixing the first paste and the second paste ofthe paste/paste GI composition disclosed herein can fulfil one, morethan one, or all of the following parameters after hardening: flexuralstrength above about 20 MPa, or above about 25 MPa, determined accordingto EN-ISO 9917-2:2010 with the proviso that for covering the compositiona glass slab is used instead of a foil; compressive strength above about100 MPa, above about 120 MPa, or above about 150 MPa, determinedaccording to EN-ISO 9917-1/2007, with the proviso that for covering thecomposition a glass slab is used instead of a foil. If desired, theseparameters can be determined as described in the Example section herein.

Compared to commercially available state of the art glass ionomercements, paste/paste GI compositions disclosed herein can be readilymixed and can provide adequate mechanical properties such as flexuralstrength and fracture toughness, without affecting other importantparameters such as setting time. Typically, the paste/paste GIcompositions disclosed herein can provide adequate adhesion to dentalsurfaces such as enamel and dentin.

ILLUSTRATIVE EMBODIMENTS OF THE PRESENT DISCLOSURE

Various embodiments are disclosed that can provide curable glass ionomercompositions and methods of using same.

Embodiment 1A is a curable glass ionomer composition comprising: a firstpaste comprising: water, a polyacid, and a non acid-reactive filler; anda second paste comprising: water, an acid-reactive filler; andnon-aggregated, water-miscible, nano-sized silica particles having atleast 25% surface coverage of the particles with a silane; wherein thecomposition is essentially free of a resin.

Embodiment 2A is the curable glass ionomer composition of Embodiment 1A,wherein the composition is free of a resin.

Embodiment 3A is the composition according to embodiment 1A or 2Awherein the silane is essentially free of unsaturated polymerizablegroups.

Embodiment 4A is the composition according to any one of embodiments 1Ato 3A wherein the silane is of the formula:(R¹O)₃—Si—(CH₂)_(n)—(O—R²)_(x)—OR³, wherein: R¹ is a C1-C3 alkyl group;R² is a C2-C3 alkylene group; R³ is a C1-C10 alkyl group; n=2 to 6; andx=0 to 200.

Embodiment 5A is the composition according to any one of embodiments 1Ato 3A wherein the silane is of the formula:(R¹O)₃—Si—(CH₂)_(n)—(O—R²)_(x)—OR³, wherein: R¹ is a C1-C3 alkyl group;R² is a C2-C3 alkylene group; R³ is 2,3-epoxypropyl; n=2 to 6; and x=0to 200.

Embodiment 6A is the composition according to embodiment 4A or 5Awherein R² represents

—CH₂CH₂—.

Embodiment 7A is the composition according to any one of embodiments 4Ato 6A wherein n=3.

Embodiment 8A is the composition according to any one of embodiments 1Ato 7A wherein the non-aggregated, water-miscible, nano-sized silicaparticles have at least 50% surface coverage of the particles with asilane.

Embodiment 9A is the composition according to any one of embodiments 1Ato 8A wherein the non-aggregated, water-miscible, nano-sized silicaparticles have at least 75% surface coverage of the particles with asilane.

Embodiment 10A is the composition according to any one of embodiments 1Ato 9A wherein the non-aggregated, water-miscible, nano-sized silicaparticles have at least 95% surface coverage of the particles with asilane.

Embodiment 11A is the composition according to any one of embodiments 1Ato 10A wherein the non-aggregated, water-miscible, nano-sized silicaparticles are substantially free of fumed silica.

Embodiment 12A is the composition according to any one of embodiments 1Ato 11A wherein at least one of the first paste and the second pastefurther comprises pyrogenic silica particles.

Embodiment 13A is the composition according to any one of embodiments 1Ato 12A wherein the water content of the first paste and the second pastecombined is less than 20% by weight, based on the total weight of thecomposition.

Embodiment 14A is the composition according to any one of embodiments 1Ato 13A wherein the water content of the first paste is less than 20% byweight, based on the total weight of the first paste; and the watercontent of the second paste is less than 20% by weight, based on thetotal weight of the second paste.

Embodiment 15A is the composition according to any one of embodiments 1Ato 14A wherein the water content of the first paste and the second pastecombined is less than 19% by weight, based on the total weight of thecomposition.

Embodiment 16A is the composition according to any one of embodiments 1Ato 15A wherein the water content of the first paste and the second pastecombined is less than 18% by weight, based on the total weight of thecomposition.

Embodiment 17A is the composition according to any one of embodiments 1Ato 16A wherein the water content of the first paste and the second pastecombined is less than 17% by weight, based on the total weight of thecomposition.

Embodiment 18A is the composition according to any one of embodiments 1Ato 17A wherein the water content of the first paste and the second pastecombined is less than 16% by weight, based on the total weight of thecomposition.

Embodiment 19A is the composition according to any one of embodiments 1Ato 18A wherein the water content of the first paste and the second pastecombined is less than 15% by weight, based on the total weight of thecomposition.

Embodiment 20A is the composition according to any one of embodiments 1Ato 19A wherein the water content of the first paste and the second pastecombined is 10% by weight to 15% by weight, based on the total weight ofthe composition.

Embodiment 21A is the composition according to any one of embodiments 1Ato 20A wherein the non acid-reactive filler comprises particles and/orfibers.

Embodiment 22A is the composition according to any one of embodiments 1Ato 21A wherein the non acid-reactive filler is selected from the groupconsisting of quartz, nitrides, kaolin, borosilicate glass, strontiumoxide based glass, barium oxide based glass, silica, alumina, titania,zirconia, and combinations thereof.

Embodiment 23A is the composition according to any one of embodiments 1Ato 22A wherein the non acid-reactive filler comprises a metal oxideselected from the group consisting of alumina, silica, zirconia,titania, and combinations thereof.

Embodiment 24A is the composition according to any one of embodiments 1Ato 23A wherein the non acid-reactive filler has a mean particle size of0.005 micrometer to 10 micrometers.

Embodiment 25A is the composition according to any one of embodiments 1Ato 24A wherein the non acid-reactive filler comprises substantiallycrystalline inorganic fibers.

Embodiment 26A is the composition according to embodiment 25A whereinthe substantially crystalline inorganic fibers comprise ceramics and/ormetal oxides.

Embodiment 27A is the composition according to embodiment 25A or 26Awherein the substantially crystalline inorganic fibers comprise a metaloxide selected from the group consisting of alumina, silica, zirconia,titania, and combinations thereof.

Embodiment 28A is the composition according to embodiment 27A whereinthe metal oxide is modified with a component selected from the groupconsisting of sodium, magnesium, lithium, calcium, strontium, barium,yttrium, ytterbium, zinc, iron, manganese, bismuth oxides, andcombinations thereof.

Embodiment 29A is the composition according to any one of embodiments25A to 28A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average diameter of at least 3micrometers.

Embodiment 30A is the composition according to any one of embodiments25A to 29A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average diameter of at most 25micrometers.

Embodiment 31A is the composition according to any one of embodiments25A to 30A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average diameter of at most 20micrometers.

Embodiment 32A is the composition according to any one of embodiments25A to 31A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average aspect ratio of about 10:1.

Embodiment 33A is the composition according to any one of embodiments25A to 32A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average length of no more than 1millimeter.

Embodiment 34A is the composition according to any one of embodiments25A to 33A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average length of no more than 0.5millimeter.

Embodiment 35A is the composition according to any one of embodiments25A to 34A wherein the substantially crystalline inorganic fibers ascontained in the pastes have an average length of at least 25micrometers.

Embodiment 36A is the composition according to any one of embodiments25A to 35A wherein the substantially crystalline inorganic fibers have acrystallinity index of at least 0.05 as measured by the XRDCrystallinity Index Test Method.

Embodiment 37A is the composition according to any one of embodiments25A to 35A wherein the substantially crystalline inorganic fibers have acrystallinity index of at least 0.1 as measured by the XRD CrystallinityIndex Test Method.

Embodiment 38A is the composition according to any one of embodiments25A to 37A wherein the first paste comprises no more than 65% by weightof the substantially crystalline inorganic fibers, based on the totalweight of the first paste.

Embodiment 39A is the composition according to any one of embodiments25A to 38A wherein the second paste comprises no more than 65% by weightof the substantially crystalline inorganic fibers, based on the totalweight of the second paste.

Embodiment 40A is the composition according to any one of embodiments25A to 39A wherein the composition comprises no more than 40% by weightof the substantially crystalline inorganic fibers, based on the totalweight of the composition.

Embodiment 41A is the composition according to any one of embodiments25A to 40A wherein the composition comprises 10% by weight to 15% byweight of the substantially crystalline inorganic fibers, based on thetotal weight of the composition.

Embodiment 42A is the composition according to any one of embodiments 1Ato 41A wherein the acid-reactive filler comprises an inorganic fillerselected from the group consisting of basic metal oxides, metalhydroxides, hydroxyapatite, aluminosilicate glasses,fluoroaluminosilicate glasses, glasses having a Si/Al weight percentratio less than 1.5, and combinations thereof.

Embodiment 43A is the composition according to any one of embodiments 1Ato 42A wherein the acid-reactive filler has a mean particle size of 3micrometers to 10 micrometers.

Embodiment 44A is the composition according to any one of embodiments 1Ato 43A wherein the first paste further comprises a complexing agent.

Embodiment 45A is the composition according to any one of embodiments 1Ato 44A wherein the composition remains sufficiently workable or mixableto form a curable glass ionomer composition after storage at roomtemperature for at least one month.

Embodiment 46A is the composition according to any one of embodiments 1Ato 45A wherein the composition remains sufficiently workable or mixableto form a curable glass ionomer composition after storage at roomtemperature for at least three months.

Embodiment 47A is the composition according to any one of embodiments 1Ato 46A wherein the composition remains sufficiently workable or mixableto form a curable glass ionomer composition after storage at roomtemperature for at least six months.

Embodiment 1B is a method of preparing a cured composition comprising:providing a curable glass ionomer composition according to any one ofembodiments 1A to 47A; combining the first paste and the second paste toform a mixture; and allowing the mixture to cure to form the curedcomposition.

Embodiment 1C is a device for storing the composition according to anyone of embodiments 1A to 47A comprising: a first compartment containingthe first paste; and a second compartment containing the second paste.

Embodiment 2C is the device of embodiment 1C, wherein both the firstcompartment and the second compartment each independently comprises anozzle or an interface for receiving an entrance orifice of a staticmixing tip.

Embodiment 1D is a method of preparing a cured composition comprising:providing a device according to embodiment 1C or 2C; combining the firstpaste and the second paste to form a mixture; and allowing the mixtureto cure to form the cured composition.

Objects and advantages of this disclosure are further illustrated by thefollowing non-limiting examples, but the particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this disclosure.

EXAMPLES

The following examples are given to illustrate, but not limit, the scopeof this invention. As used herein, all parts and percentages are byweight and all water was deionized, unless otherwise specified. Unlessotherwise specified, materials can be obtained from Sigma-Aldrich Corp.(St. Louis, Mo.). All commercial materials were used as obtained fromthe vendor. Ammonium fluoride was obtained from Alfa Aesar (Tewksbury,Mass.). Tartaric acid was obtained from Fisher Scientific (Waltham,Mass.), 3-Phosphonopropionic acid was obtained from Alfa Aesar(Tewksbury, Mass.).

XRD Crystallinity Index Test Method

The Crystallinity Index is a parameter used to characterize the level ofcrystallinity present in a sample of an inorganic fiber. In brief, inthe XRD Crystallinity Index Test Method used herein, tungsten powder isused as internal standard. An internal or mass standard refers to amaterial incorporated into samples being evaluated to determinecrystallinity index, to normalize X-ray intensity values based on amountof material present in sample. Each inorganic fiber sample tested ismixed with tungsten powder in a 4:1 ratio by weight. Each inorganicfiber sample preparation is mixed as an ethanol slurry and then dried,and two sample preparations are made for each inorganic fiber sampletested. Six XRD scans of each sample preparation are then taken. Thecrystallinity index is the ratio of peak area observed for analytecrystalline phase diffraction peaks within the 14 to 46 degree (2Theta)scattering angle range and the (110) diffraction peak area for thetungsten internal standard. The following procedure was used to measurethe XRD Crystallinity Index for the tested substantially crystallineinorganic fibers.

Particle size of the phase standard was reduced by ball milling and/orhand grinding in a boron carbide mortar and pestle to pass 325 meshsieve. Individual mixtures were prepared consisting of 0.400 grams ofeach sample and 0.100 grams of tungsten internal standard (i.e.,tungsten metal powder, <3 micron, available from General Electric, LotU-1.35-8808D). Mixtures were blended under ethanol in a mortar andpestle and allowed to dry under flowing nitrogen. The dried mixtureswere removed from the mortar and pestle by spatula and fine brush andfinally transferred to individual sample containers.

Portions of each sample were prepared as ethanol slurries on zerobackground specimen holders composed of silicon. Multiple X-raydiffraction scans were obtained from each sample by use of aBragg-Bretano theta-theta diffractometer (Empyrean, constructed byPANalytical, Almelo, The Netherlands) employing copper K_(α) radiation,variable entrance slit, fixed exit slit, and Pixcel detector registry ofthe scattered radiation. Scans were conducted from 14 to 46 degrees (20)employing a 0.026 degree step size and 10 second dwell time. The X-raygenerator was operated at a setting of 40 kV and 40 mA and fixedincident beam slits were used.

Peak areas for the observed diffraction maxima due to crystalline phaseswithin the sample and tungsten mass standard were measured by profilefitting observed diffraction peaks within the 14-46 degree (20)scattering angle range. The X-ray scattering of internal mass standardwas evaluated by measurement of cubic tungsten using the (11 0) peakarea. When necessary, the scattering due to amorphous phases wasaccounted for by including a sufficient number of suitably broadscattering peaks during the profile fitting procedure. A Pearson VIIpeak shape model and linear background model were employed in all cases.The profile fitting was accomplished by use of the capabilities of theJADE (Version 9, Materials Data Inc. Livermore, Calif.) diffractionsoftware suite.

The peak areas for maxima produced by crystalline phases present in thesample were summed to produce a total sample crystalline phase scatteredintensity value [(Total Crystalline Area)_(sample)] for each sample. Anybroad peaks used to account for amorphous phases during profile fittingwere not included in crystallinity index calculations. These totalsample crystalline phase scattered intensity values were divided byrespective cubic tungsten (11 0) peak area to produce the crystallinityindex [X_(c)] for each sample:X _(c)═[(Total Crystalline Area)_(sample)]/[(Tungsten Area)sample]The mean X_(c) value was calculated from individual X_(c) values:X _(c(mean))=[ΣX _(c(i))]/N _(sample),where N_(sample)=number of sample scans. Multiple XRD runs of a samplewere reported.

The Crystallinity Index results measured according to this procedure arereported in Table 1.

TABLE 1 Measured Crystallinity Indices Crystallinity Index (std. dev.)Sample Sample Preparation 1 Sample Preparation 2 Nextel 312 0 0 Nextel720 1.82 (0.71) 1.51 (0.40) Zirconia 3.87 (0.98) 4.08 (2.58) Corundum0.94 (0.12) 0.79 (0.07) (approximately 100% crystalline) Nextel 6101500d 0.82 (0.03) 0.70 (0.03)No detectable diffraction peaks were observed for the Nextel 312samples.Materials

“NALCO 2329” refers to an aqueous colloidal silica sol containing 40 wt.% SiO₂, sodium counter ion (approximately 0.25% Na₂O), pH=8.4 at 25° C.,75 nm particle size, available from Ecolab (Naperville, Ill.);

“LEVASIL 50/50” refers to an aqueous colloidal silica sol containing 50wt. % SiO₂, base-stabilized colloidal silica sol, pH=9-10, 50 nmparticle size, available from Akzo Nobel (Bohus, Sweden);

“PA 1” refers to a water soluble polyacid copolymer of acrylic acid andmaleic acid (1:1 copolymer) with a MW of approximately 20,000 (KETAC-FILPLUS (3M ESPE Dental Products);

“FAS 1” refers to an acid-reactive fluoroaluminosilicate glass powder,mean particle size: 4.8 μm (d10 of 1.6 μm; d508.0 μm; d90 of 30 μm) withthe following elemental composition: Si: 10-15 wt. %; Al: 10-15 wt. %;Sr: 23-26.5 wt. %; Na: 2.0-4.0 wt. %; F: 11.0-14.5 wt. %; P: 2-3.5 wt.%; La: 4.5-7 wt. %; 0: 26-30 wt. % (based on X-ray fluorescenceanalysis). The acid reactive glass powder is prepared by melting a glassfrit, subsequently crushing and grinding the frit to particle size of4.8 rpm, followed by washing with 1M hydrochloric acid for 1 hour,filtering, drying and tempering at 200-300° C. for 12 hours.

“FAS 2” refers to an acid-reactive fluoroaluminosilicate glass powder,mean particle size: 4.8 μm with the following elemental composition: Si:7.5-12.5 wt. %; Al: 7.5-12.5 wt. %; La: 15.0-20.0 wt. %; Ca: 7.5-12.5wt. %; Na: 1.0-3.0 wt. %; P: 0.5-3.0 wt. %; F: 12.0-17.0 wt. %; O:30.0-35.0 wt. % (based on X-ray fluorescence analysis). The acidreactive glass powder is prepared by melting a glass frit, subsequentlycrushing and grinding the frit to particle size of 4.8 m, followed bywashing with 1M hydrochloric acid for 1 hour, filtering, drying andtempering at 200-300° C. for 12 hours.

“NEXTEL 720” refers to aluminosilica ceramic fibers having α-Al₂O₃ andMullite crystal phases (85 wt. % Al₂O₃, 15 wt. % SiO₂), 10-12 μmdiameter, available from 3M which were further chopped to uniformlengths of 200 μm. “S/T NEXTEL 720” refers to NEXTEL 720 which wassurface-treated as follows. To a stirring mixture of the chopped fiberin water (5 times the weight of the chopped fiber) was added3-phosphonopropionic acid (2 wt. %, based on the weight of the fiber).The mixture was heated to 100° C. and stirred for a minimum of 2 hours.The fibers were allowed to settle approximately 30 minutes), and thesupernatant liquid decanted. The fibers were washed with excess water(twice) and the damp fibers were dried at 85° C. for approximately 2hours to provide the NEXTEL 720 chopped fibers.

“Silquest A-1230” refers to a polyalkyleneoxidealkoxysilane with amolecular weight of approximately 600 g/mol, obtained from MomentivePerformance Materials (Waterford, N.Y.).

“Methoxypropyltrimethoxysilane” refers to a hydrophilic silane with amolecular weight of 194 g/mol, obtained from Gelest, Inc (Morrisville,Pa.).

“Carboxyethylsilanetriol” refers to a hydrophilic silane with amolecular weight of 196 g/mol, obtained from Gelest, Inc (Morrisville,Pa.).

“Acetoxyethyltrimethoxysilane” refers to a hydrophilic silane with amolecular weight of 208 g/mol, obtained from Gelest, Inc (Morrisville,Pa.).

“Aerosil 300 Pharma” refers to a fumed silica with a surface area ofabout 300 m²/g, obtained from Evonik Industries (Essen, Germany).

Methods

Preparation of Silane-Treated Silica Sols

Silane treatments were performed by reacting a solution of silica sol(such as Levasil 50/50 or Nalco 2329) with a silane (such as SilquestA-1230). The ratio of silane to silica sol for a “100% theoreticalcoverage” was calculated by using Equation 1 shown below:

$\begin{matrix}{\frac{g\mspace{14mu}{silane}}{g\mspace{14mu}{silica}\mspace{14mu}{sol}} = {6.25 \times 10^{{- 4}\mspace{11mu}{mol}}\text{/}g \times \frac{20\mspace{14mu}{nm}}{d} \times {MW} \times {SiO}\; 2\mspace{14mu} w\text{/}w}} & (1)\end{matrix}$Where d is the diameter of the silica particle (nm), MW is the molecularweight of the silane (g/mol), and SiO2 w/w is the silica weight fractionof the silica sol (w/w). For example, if Levasil 50/50 was the silicasol being used, and 3-glycidoxypropyltrimethoxysilane was the silane,the ratio for “100% theoretical coverage” would have been calculated asfollows:

$\begin{matrix}{\frac{g\mspace{14mu}{silane}}{g\mspace{14mu}{Levasil}\mspace{14mu} 50\text{/}50} = {6.25 \times 10^{{- 4}\mspace{14mu}}{mol}\text{/}g \times \frac{20\mspace{14mu}{nm}}{50\mspace{14mu}{nm}} \times}} \\{236.3\mspace{14mu} g\text{/}{mol} \times 0.5} \\{= {{.03}\;\frac{g\mspace{14mu}{silane}}{g\mspace{14mu}{Levasil}\mspace{14mu} 50\text{/}50}}}\end{matrix}$

Once the correct amounts of silica sol and silane were added into avessel (usually a glass vial or glass jar), the solution would beallowed to react. The most common reaction conditions were 80-85 C for17 hours; however, the exact temperature and time is not overlysignificant. Once the reaction time was complete, the silane-treatmentwas done, and the sol was ready to use.

Preparation of Glass Ionomer Pastes Generally

All pastes were created by using a high shear speed mixer (FlackTek Inc.Speed Mixer, DAC 150 FVZ & 150.1 FVZ). Base pastes were created byadding all ingredients, and mixing at 2000-2500 RPM for 1 minute. Thistended to be enough for a complete mix of the base paste. Acid pasteswere created by addition of water, tartaric acid, and PA 1. The solutionwas then speed mixed at 3500 RPM for 1 minute, to break up the solids.S/T Nextel 720 fiber was then added, and the paste was speed mixed at3500 RPM for 1 minute. This was then followed by a series ofhand-spatulating followed by speed mixing at 3500 RPM for 1 minute untila homogenous paste was achieved.

Flexural Strength

Glass ionomer test specimens were prepared by mixing the two parts atthe ratios indicated in the tables below, and placing the mixed materialinto a 2 millimeter×2 millimeter×25 millimeter PEEK (polyether etherketone) mold with polyester film on both sides. Polycarbonate slideswere placed outside of both pieces of polyester film. The mold was thenclamped with a power hand clamp and put into a temperature and humiditycontrolled chamber for about 1 hour at 37° C. and 95% relative humidity.The sample was then removed from mold, placed into deionized water, andput into a 37° C. oven for about 24 hours. Samples were then polishedusing 600 grit sandpaper on a Buehler Ecomet 4 Variable SpeedGrinder-Polisher to smooth edges, and accurately measure width andlength. Flexural strength was measured on an Instron tester (Instron5944, Instron Corp., Canton, Mass., USA) according to ANSI/ADA (AmericanNational Standard/American Dental Association) specification No. 27(1993) at a crosshead speed of 0.75 millimeer/minute.

Storage Stability

Pastes of the example compositions were placed into BD Slip Tip syringes(5 or 10 mL) and dispensed into heat-sealable aluminum pouches. Poucheswere heat-sealed to be air-tight and water-tight, labelled, and massed.10-15 pouches of paste were made for each formulation. Pouches wereplaced into a plastic zipper-closing bag, and placed into a 25° C., 50%Relative Humidity environment. Samples were observed for aging atvarious time points. Samples were massed before observing to verify thatno water loss had taken place. At end of each respective storage timeperiod, examples were opened and evaluated with a probe for softness andworkability as an acceptable paste. Sample results were grouped intothree rating categories: (1) “++” indicated the samples exhibited nonoticeable change over the storage conditions, they were still a softworkable, mixable paste and considered acceptable; (2) “+” indicated theexamples exhibited some amount of change, they were not as soft but werestill a workable, mixable paste and marginally acceptable; (3) “−”indicated the samples exhibited definite unacceptable change, they werea hardened paste and not workable. Stability results are shown in Tables30-32.

Formulations

Silane-Treated Silica Sols

The silane-treated silica sols which were used in experimentation can beseen below in Tables 2-5:

TABLE 2 A-1230 Silane-Treated Silica Sol Formulations % TheoreticalCoverage Silica Sol Name % Silica Sol % A-1230 Silane 100% Levasil 50/5093.0% 7.0% 100% Nalco 2329 96.5% 3.5% 75% Levasil 50/50 94.7% 5.3% 75%Nalco 2329 97.4% 2.6% 50% Levasil 50/50 96.4% 3.6% 50% Nalco 2329 98.2%1.8% 25% Levasil 50/50 98.2% 1.8% 25% Nalco 2329 99.1% 0.9% 10% Levasil50/50 99.2% 0.8%

TABLE 3 Methoxypropyltrimethoxysilane-Treated Silica Sol Formulations %Theoretical Silica Sol % Silica % Coverage Name SolMethoxypropyltrimethoxysilane 100% Levasil 50/50 97.6% 2.4% 50% Levasil50/50 98.7% 1.3% 25% Levasil 50/50 99.3% 0.7%

TABLE 4 Carboxyethylsilanetriol-Treated Silica Sol Formulations %Theoretical Silica Sol % Coverage Name % Silica SolCarboxyethylsilanetriol 100% Levasil 50/50 97.9% 2.1% 50% Levasil 50/5098.9% 1.1% 25% Levasil 50/50 99.4% 0.6%

TABLE 5 Acetoxyethyltrimethoxysilane-Treated Silica Sol Formulations %Theoretical Silica Sol % Silica % Coverage Name SolAcetoxyethyltrimethoxysilane 100% Levasil 50/50 97.5% 2.5% *This solgelled upon reaction and had a mashed potatoes-like consistencyPaste FormulationsThe base pastes which were created for storage stability testing can beseen below in Tables 6-23:

TABLE 6 Paste Formulation of Comparative Example 1 for Storage StabilityTesting Comparative Example 1 Material Weight % FAS 1 80.8 Levasil 50/5019.2

TABLE 7 Paste Formulation of Example 1 for Storage Stability TestingExample 1 Material Weight % FAS 1 80.0 25% A-1230 Coverage Levasil 50/5019.0 Aerosil 300 Pharma 1.0

TABLE 8 Paste Formulation of Example 2 for Storage Stability TestingExample 2 Material Weight % FAS 1 80.0 50% A-1230 Coverage Levasil 50/5019.0 Aerosil 300 Pharma 1.0

TABLE 9 Paste Formulation of Example 3 for Storage Stability TestingExample 3 Material Weight % FAS 1 82.2 50% A-1230 Coverage Nalco 232916.9 Aerosil 300 Pharma 1.0

TABLE 10 Paste Formulation of Example 4 for Storage Stability TestingExample 4 Material Weight % FAS 1 78.8 100% A-1230 Coverage Levasil50/50 19.2 Aerosil 300 Pharma 2.0

TABLE 11 Paste Formulation of Example 5 for Storage Stability TestingExample 5 Material Weight % FAS 1 81.2 100% A-1230 Coverage Nalco 232916.9 Aerosil 300 Pharma 2.0

TABLE 12 Paste Formulation of Comparative Example 2 for StorageStability Testing Comparative Example 2 Material Weight % FAS 2 73.0Levasil 50/50 26.0 Aerosil 300 Pharma 1.0

TABLE 13 Paste Formulation of Comparative Example 3 for StorageStability Testing Comparative Example 3 Material Weight % FAS 2 73.0 10%A-1230 Coverage Levasil 50/50 26.0 Aerosil 300 Pharma 1.0

TABLE 14 Paste Formulation of Example 6 for Storage Stability TestingExample 6 Material Weight % FAS 2 73.0 25% A-1230 Coverage Levasil 50/5026.0 Aerosil 300 Pharma 1.0

TABLE 15 Paste Formulation of Example 7 for Storage Stability TestingExample 7 Material Weight % FAS 2 73.0 50% A-1230 Coverage Levasil 50/5026.0 Aerosil 300 Pharma 1.0

TABLE 16 Paste Formulation of Example 8 for Storage Stability TestingExample 8 Material Weight % FAS 2 73.0 100% A-1230 Coverage Levasil50/50 26.0 Aerosil 300 Pharma 1.0

TABLE 17 Paste Formulation of Example 9 for Storage Stability TestingExample 9 Material Weight % FAS 2 73.0 25% MethoxypropyltrimethoxysilaneCoverage 26.0 Levasil 50/50 Aerosil 300 Pharma 1.0

TABLE 18 Paste Formulation of Example 10 for Storage Stability TestingExample 10 Material Weight % FAS 2 73.0 50%Methoxypropyltrimethoxysilane Coverage 26.0 Levasil 50/50 Aerosil 300Pharma 1.0

TABLE 19 Paste Formulation of Example 11 for Storage Stability TestingExample 11 Material Weight % FAS 2 73.0 100%Methoxypropyltrimethoxysilane Coverage 26.0 Levasil 50/50 Aerosil 300Pharma 1.0

TABLE 20 Paste Formulation of Comparative Example 4 for StorageStability Testing Comparative Example 4 Material Weight % FAS 2 73.0 25%Carboxyethylsilanetriol Coverage Levasil 50/50 26.0 Aerosil 300 Pharma1.0

TABLE 21 Paste Formulation of Comparative Example 5 for StorageStability Testing Comparative Example 5 Material Weight % FAS 2 73.0 50%Carboxyethylsilanetriol Coverage Levasil 50/50 26.0 Aerosil 300 Pharma1.0

TABLE 22 Paste Formulation of Comparative Example 6 for StorageStability Testing Comparative Example 6 Material Weight % FAS 2 73.0100% Carboxyethylsilanetriol Coverage Levasil 50/50 26.0 Aerosil 300Pharma 1.0

TABLE 23 Paste Formulation of Comparative Example 7 for StorageStability Testing Comparative Example 7 Material Weight % FAS 2 73.0100% Acetoxyethyltrimethoxysilane Coverage Levasil 26.0 50/50 Aerosil300 Pharma 1.0 *This formulation did not make an acceptable pasteThe formulations which were used to test flexural strength are shownbelow in Tables 24-29:

TABLE 24 Paste Formulations of Comparative Example 8 for FlexuralStrength Testing Comparative Example 8 (1:0.9 weight ratio of acidpaste:base paste) Acid Paste Base Paste Overall Material (wt %) (wt %)(wt %) Water 9.0% — 4.7% Tartaric Acid 3.0% — 1.6% PA 26.0%  — 13.7%Nextel 720 — 10.0% 4.7% S/T Nextel 720 56.0%  — 29.5% FAS 2 — 66.0%31.3% Levasil 50/50 6.0% 24.0% 14.5%

TABLE 25 Paste Formulations of Example 12 for Flexural Strength TestingExample 12 (1:0.9 weight ratio of acid paste:base paste) Acid Paste BasePaste Overall Material (wt %) (wt %) (wt %) Water 9.0% — 4.7% TartaricAcid 3.0% — 1.6% PA 26.0%  — 13.7% Nextel 720 — 10.0% 4.7% S/T Nextel720 56.0%  — 29.5% FAS 2 — 66.0% 31.3% Levasil 50/50 6.0% — 3.2% 25%A-1230 Coverage Levasil 50/50 24.0% 11.4%

TABLE 26 Paste Formulations of Example 13 for Flexural Strength TestingExample 13 (1:0.9 weight ratio of acid paste:base paste) Acid Paste BasePaste Overall Material (wt %) (wt %) (wt %) Water 9.0% — 4.7% TartaricAcid 3.0% — 1.6% PA 26.0%  — 13.7% Nextel 720 — 10.0% 4.7% S/T Nextel720 56.0%  — 29.5% FAS 2 — 66.0% 31.3% Levasil 50/50 6.0% — 3.2% 50%A-1230 Coverage Levasil 50/50 24.0% 11.4%

TABLE 27 Paste Formulations of Example 14 for Flexural Strength TestingExample 14 (1:0.9 weight ratio of acid paste:base paste) Acid Paste BasePaste Overall Material (wt %) (wt %) (wt %) Water 9.0% — 4.7% TartaricAcid 3.0% — 1.6% PA 26.0%  — 13.7% Nextel 720 — 10.4% 4.9% S/T Nextel720 56.0%  — 29.5% FAS 2 — 68.8% 32.6% Levasil 50/50 6.0% — 3.2% 50%A-1230 Coverage Nalco 2329 20.8% 9.9%

TABLE 28 Paste Formulations of Example 15 for Flexural Strength TestingExample 15 (1:0.9 weight ratio of acid paste:base paste) Acid Paste BasePaste Overall Material (wt %) (wt %) (wt %) Water 9.0% — 4.7% TartaricAcid 3.0% — 1.6% PA 26.0%  — 13.7% Nextel 720 — 10.0% 4.7% S/T Nextel720 56.0%  — 29.5% FAS 2 — 66.0% 31.3% Levasil 50/50 6.0% — 3.2% 100%A-1230 Coverage Levasil 24.0% 11.4% 50/50

TABLE 29 Paste Formulations of Example 16 for Flexural Strength TestingExample 16 (1:0.9 weight ratio of acid paste:base paste) Acid Paste BasePaste Overall Material (wt %) (wt %) (wt %) Water 9.0% — 4.7% TartaricAcid 3.0% — 1.6% PA 26.0%  — 13.7% Nextel 720 — 10.4% 4.9% S/T Nextel720 56.0%  — 29.5% FAS 2 — 68.8% 32.6% Levasil 50/50 6.0% — 3.2% 100%A-1230 Coverage Nalco 2329 20.8% 9.9%Physical Properties MeasurementStability was measured as described herein for exemplary examples andcomparative examples, and the results are shown in Tables 30-32:

TABLE 30 Aging Results of Base Pastes with A-1230 Silane Example Number2 Weeks 3 Weeks 1 Month 2 Month 3 Month 6 Month Comp. Example 1 N/A ++++ + + − Example 1 N/A ++ ++ ++ ++ ++ Example 2 N/A ++ ++ ++ ++ ++Example 3 N/A ++ ++ ++ ++ ++ Example 4 N/A ++ ++ ++ ++ ++ Example 5 N/A++ ++ ++ ++ ++ Comp. Example 2 + + − − − − Comp. Example 3 ++ + + + + −Example 6 ++ ++ ++ ++ ++ + Example 7 ++ ++ ++ ++ ++ ++ Example 8 ++ ++++ ++ ++ ++In the above table sample results were grouped into three ratingcategories: (1) “++” indicated the samples exhibited no noticeablechange over the storage conditions, they were still a soft workable,mixable paste and considered acceptable; (2) “+” indicated the examplesexhibited some amount of change, they were not as soft but were still aworkable, mixable paste and marginally acceptable; (3) “−” indicated thesamples exhibited definite unacceptable change, they were a hardenedpaste and not workable.

TABLE 31 Aging Results of Base Pastes with MethoxypropyltrimethoxysilaneExample Number 2 Weeks 3 Weeks 1 Month 2 Month 3 Month Example 9 ++ ++++ ++ ++ Example 10 ++ ++ ++ ++ ++ Example 11 ++ ++ ++ ++ ++It can be seen that all Examples with methoxypropyltrimethoxysilane didnot show signs of aging.

TABLE 32 Aging Results of Base Pastes with CarboxyethylsilanetriolExample Number 2 Weeks 1 Month 2 Month 3 Month Comp. Example 4 ++ ++ + −Comp. Example 5 ++ ++ + − Comp. Example 6 ++ ++ ++ +Flexural strengths were measured as described herein for exemplaryexamples and comparative examples, and the results are shown in Table33:

TABLE 33 Flexural Strength Analysis of Varying Coverages ofSilane-Treated Silica Sols % A-1230 Standard Coverage/ Mean DeviationMaterial ID Silica Sol (MPa) (MPa) Sample Size (n) Comparative 0%/ 55.156.35 5 Example 8 Levasil Example 12 25%/ 51.45 4.20 4 Levasil Example 1350%/ 48.61 5.74 5 Levasil Example 14 50%/ 53.12 8.32 5 Nalco Example 15100%/ 43.41 3.12 4 Levasil Example 16 100%/ 47.11 5.62 5 NalcoIt can be seen that while there might be a very slight trend of lowerflexural strength with higher theoretical coverage, there is not astatistical significance in flexural strength based on silane-treatmentof the silica sol.

Example 17

Example 17 was prepared with the following amounts. Levasil 50/50 fromAkzo Nobel was first epoxy silanized according to the proceduredescribed in U.S. Pat. No. 6,899,948 B2 (Zhang et al.), section “FillerC Nano-sized Silica.” The silane was 3-Glycidyloxypropyltrimethoxysilane. An amount of 15.2% epoxy silanized Levasil 50/50(containing 50% water and 50% silanized particles) was added to anamount of 83.1% Ketac Fil Plus ionomer glass powder (KETAC Fil PlusGlass Ionomer Filling Material, available from 3M Company, SeefeldGermany), 1.6% OX-50 fumed silica and 0.1% benzoic acid.

All cited references, patents, or patent applications in the aboveapplication for letters patent are herein incorporated by reference intheir entirety in a consistent manner. In the event of inconsistenciesor contradictions between portions of the incorporated references andthis application, the information in the preceding description shallcontrol. The preceding description, given in order to enable one ofordinary skill in the art to practice the claimed disclosure, is not tobe construed as limiting the scope of the disclosure, which is definedby the claims and all equivalents thereto.

What is claimed is:
 1. A curable glass ionomer composition comprising: afirst paste comprising: water, a polyacid, and a non acid-reactivefiller; and a second paste comprising: water, an acid-reactive filler;and non-aggregated, water-miscible, nano-sized silica particles havingat least 25% surface coverage of the particles with a silane; whereinthe composition is essentially free of a resin.
 2. The composition ofclaim 1, or wherein the silane is essentially free of unsaturatedpolymerizable groups.
 3. The composition of claim 1, wherein the silaneis represented by the formula:(R¹O)₃—Si—(CH₂)_(n)—(O—R²)_(x)—OR³, wherein: R¹ is a C1-C3 alkyl group;R² is a C2-C3 alkylene group; R³ is a C1-C10 alkyl group or2,3-epoxypropyl; n=2 to 6; and x=0 to
 200. 4. The composition of claim3, or wherein R² represents —CH₂CH₂—.
 5. The composition of claim 3,wherein n=3.
 6. The composition of claim 1, wherein the non-aggregated,water-miscible, nano-sized silica particles are substantially free offumed silica.
 7. The composition of claim 1, wherein at least one of thefirst paste and the second paste further comprises pyrogenic silicaparticles.
 8. The composition of claim 1, wherein the water content ofthe first paste and the second paste combined is less than 20% byweight, based on the total weight of the composition.
 9. The compositionof claim 1, wherein the non acid-reactive filler comprises particlesand/or fibers.
 10. The composition of claim 1, wherein the nonacid-reactive filler is selected from the group consisting of quartz,nitrides, kaolin, borosilicate glass, strontium oxide based glass,barium oxide based glass, silica, alumina, titania, zirconia, andcombinations thereof.
 11. The composition of claim 1, wherein the nonacid-reactive filler comprises substantially crystalline inorganicfibers.
 12. The composition of claim 11, wherein the substantiallycrystalline inorganic fibers comprise ceramics and/or metal oxides. 13.The composition of claim 11, wherein the substantially crystallineinorganic fibers have a crystallinity index of at least 0.05 as measuredby the XRD Crystallinity Index Test Method.
 14. The composition of claim1, wherein the acid-reactive filler comprises an inorganic fillerselected from the group consisting of basic metal oxides, metalhydroxides, hydroxyapatite, aluminosilicate glasses,fluoroaluminosilicate glasses, glasses having a Si/Al weight percentratio less than 1.5, and combinations thereof.
 15. The composition ofclaim 1, wherein the acid-reactive filler has a mean particle size of 3micrometers to 10 micrometers.
 16. The composition of claim 1, whereinthe first paste further comprises a complexing agent.
 17. Thecomposition of claim 1, wherein the composition remains sufficientlyworkable or mixable to form a curable glass ionomer composition afterstorage at room temperature for at least one month.
 18. The compositionof claim 1, wherein the composition remains sufficiently workable ormixable to form a curable glass ionomer composition after storage atroom temperature for at least three months.
 19. A method of preparing acured composition comprising: providing a curable glass ionomercomposition of claim 1; combining the first paste and the second pasteto form a mixture; and allowing the mixture to cure to form the curedcomposition.
 20. A device for storing a composition of claim 1, thedevice comprising: a first compartment containing the first paste; and asecond compartment containing the second paste.